Removable insulating base for a metallic junction block for cables



Feb. 13, 1962 BLANCHET 3,021,501

SE FOR A METALLIC L. REMOVABLE INSULATING BA JUNC N BLOCK FOR CABLES F'd Dec. 14, 1960 INVENTOR Lucien filanciet ATTORNEYS United States PatentOfitice 3,021,501 Patented Feb. 13, 1962 3,921,501 REMOVABLE INSULATINGBASE FOR A lVIETAL- LIC JUNCTION BLOCK FOR CABLES Lucien Blauchet, 35Rue du Cinq Mars, Colombes (Seine), France Filed Dec. 14, 1960, Ser. No.75,839 Claims priority, application France Dec. 21, 1959 Claims. (Cl.339198) In my US. Patent No. 2,983,897, I have shown how it is possibleto mount metallic junction blocks provided with wire-holding clamps onbases provided with a central terminal and adapted to be snapped onto acommon support in the form of a rail, insulating partitions beinginterposed between adjacent bases to avoid any undesired electricalcontact between the metallic junction blocks mounted on adjacent bases.

In my copending US. patent application S.N. 59,967, I also describedbases made of an insulating material having a central terminal andprovided with a vertical partition insuring insulation between theterminals on adjacent bases, and carrying projections to which a covercould be attached.

The present invention relates to a base made of a molded insulatingmaterial which may be a superpolyamide of the nylon type, such as thematerial sold in France under the trademark Rilson. This may be snappedonto a common support in the form of a rail, said base likewisecomprising a thin vertical plate serving as an intercalary partitionbetween adjacent bases, and projections onto which a cover can besnapped, said base being adapted to receive a metallic junction blockprovided with two wire clamps, this new base being characterized by thefact that the metallic junction block is held transversely between threemembers made of molded insulating material projecting out from said thinvertical plate the lower member serving to enable the base to be snappedonto the common support, and the two upper members each being providedwith grooves for holding an indicating label.

Another characteristic of the present invention relates to the means forimmobilizing the metallic junction block a ainst longitudinal movementwith respect to its base. This immobilization is assured by means of thesame members which serve to bring pressure against the ends of thecables, or to attach shunts connecting the metallic blocks carried byadjacent bases.

The metallic block carries for this purpose, in addition to the twobores through which the ends of the cables pass and the three tappedholes which cooperate respectively either with the clamping screws orthe shunt attaching screw, two circular bores which receive twocylindrical insulating plugs which are parallel to the common supportingrail, and of the same length as the three aforesaid projections, thediameter and position of these plugs being so chosen that when theclamping screws are tightened, the threads of these screws cut a passagethrough the somewhat elastic insulating material of which thecylindrical plugs are made.

It may also comprise two grooves which cooperate with tongues on the twoupper members, which serve as label holders, these grooves being sopositioned that the clamping screws cut into the insulating material ofthese two upper members.

In the same way, the screws for connecting a shunt should also make apassageway for themselves by tapping the insulating material of said twocylindrical plugs.

It is easy to understand that when the two screws are screwed down togrip the ends of the cables, they are at the same time frictionallygripped by the somewhat elastic insulating material through which theypass, whether this material is that of the label holders or that of saidcylindrical buttons.

This frictional gripping prevents the screws from working loose whensubjected to vibrations, and at the same time insures that the metallicblock is immobilized with respect to the insulating base so as toprevent movement in a longitudinal direction parallel to the commonsupporting rail.

When a shunt is attached, the shunt screw likewise serves two purposes,i.e., it cooperates in the immobilization of the metallic block againstlongitudinal movement with respect to its base, and it also attaches ashunt connecting the metallic junction blocks carried by two adjacentbases, the contact with the somewhat elastic insulating material of thetwo cylindrical plugs serving to restrain any turning of the shuntattaching screw.

Other characteristics of the present invention will be better understoodfrom a reading of the following description of one embodiment of a basemade of insulating material which carries a metallic junction block.This description is given purely by way of example, without limiting thescope of the invention to the details thereof, and is illustrated by theaccompanying drawing in which:

FIG. 1 is a perspective view showing a base made of insulating materialin accordance with the present invention, equipped with a metallicjunction block; and

FIG. 2 is a central transverse cross-section taken through the axes ofthe screws for clamping the cables. As shown on FIG. 1, the terminalsupport mounted on the common rails 1 comprises a thin portion 2 whichserves as an intermediate partition between adjacent blocks, a base 3provided with depending projections 24 adapted to snap onto said rail,and two side members 4 and 5 which serve both as a label holder and asmeans for holding the metallic junction block against transversemovement.

The block 6 comprises two bores 7 in its lower part, only one of whichbores is visible on FIG. 1. The bare, ends of the cables 8 which are tobe connected to the block 6 extend into these bores.

The upper part of the thin plate 2 is provided with two protuberances 9and 10 designed to cooperate with mating snap attaching means on aprotective cover for a group of contiguous blocks.

The screws 11 and 12 which serve to exert a pressure on the metallicferrules of cables 8 are preferably of the type having a head in theform of a hexagonal socket, as shown in particular at 13 on FIG. 2. Theyalso preferably comprise at their lower ends a small central hollow 14,instead of ending in a point, so that these screws bear on the metallicferrules of the cables 8, along a circular line of contact.

The members 4 and 5 are provided with grooves 15 for holding labels.

Besides the members 4 and 5, the block 6 is held in place by means oftwo cylindrical plugs 16 and 17 of a length equal to the thickness ofthe metallic junction block. These plugs are seated in bores providedfor this purpose in the junction block 6.

As shown in cross-section on FIG. 2, the members 4 and 5 each comprisean inwardly extending portion, such as the tongue 18, which projectsinto the bore in the metallic junction block 6. i

The screw 12 is shown in FIG. 2 before its introduction into the tappedhole 19 in the metallic junction block 6, so that it is easy tounderstand that this screw 12 can be tightened down on the end of acable only after abrading a path for itself through the insulatingmaterial of one of the tongues 18 and the cylindrical plug 17.

The screw 11, which is shown in its lower position, has acted as a tapand extended the tapping 19 in the junction block 6 to parts 4 and 16 asshown at 20 and 21.

permit contact between It will be readily understood that by reason ofthe elasticity of the plastic insulating material used to make the basefor the block, the screw 11 after being tightened downon'thebare end ofja'cable' 8, is preventedfrom loosening by its frictional engagementwith the insulating material in the portions 26 and 21 of the tongue 18of the member 4 and the cylindrical plug 16, respectively.

Moreover, the penetration of the screws 11 and 12 into the insulatingmaterial of the tongues 18 and plugs 16 and 17 also insures that thejunction block, 6 is prevented from moving longitudinally with respectto its support and kept in contact with the portion 2 of this supportwhich serves as an intercalary partition.

There is a tapped hole 22 in the center of the block 6 into which ascrew may be inserted in order to attach a shunt 23 which may connecttwo adjacent junction blocks 6. This insures an adequateelectricalcontact between the two blocks, which would not be the case if onesimply so positioned the intercalary plates 2 so as to two adjacentmetallic junction blocks.

When a shunt screw such as shown at 22' in FIG. 1 is screwed in, thisscrew cuts itself a path in the insulating material forming thecylindrical plugs 16 and 17, acting as a tap, and is fiictionally heldin position in which it immobilizes the shunt, in the same manner as theclamping screws bearing on the bare ends of the cables 8. Once screwedin, the shunt screws help to prevent longitudinal movement of the blocks6 on their bases.

It is clear that the arrangement of the label holding means 4 and 5 maybe differentand that the tongue 18 may be replaced by a projectingshoulder extending, for example, to the upper part of the block 6.

The position of the tongue shown on FIG. 2 has been adopted because ofthe greater solidity with which it permits the metallic blocks 6 to bemade.

It will be readily understoodthat the particular embodiment which hasbeen described may be altered as to detail, improved, or added to, andthat certain elements thereof may be replaced by their mechanicalequivalents, without thereby departing from the spirit of the inventionas defined by the following claims.

What I claim is:

1. In combination, a metallic junction block of the type provided withsockets for receiving the ends of con- 4. ductors and threadedpassageways intersecting said sockets, said passageways being adapted toreceive screws for clamping the ends. of said conductors to said block,and an insulating support for said block, said support being made of aresilient insulating material and comprising a vertical platedimensioned to shield one side of said block and a plurality ofprojections extending from one side of said plate, said junction blockbeing provided with openings mating with and receiving said projections,the peripheries of said openings intersecting the peripheries of saidthreaded passageways, so that when screws are screwed into saidpassageways, the threads thereon cut into said projections and theresilient material thereof frictionally grips said screws, so as toresist withdrawal of either said screws or said projections from saidblock.

2. A junction block and support as claimed in claim 1 in which saidprojections comprise two cylindrical plugs and two label carrierspositioned at opposite ends of said plate, said label carriers eachcomprising a tongue seated in one of the mating openings in said block.3;v A junction block and support as claimed in claim 2 in which saidblock comprises an additional threaded passageway adapted to receive ascrew for connecting a shunt, said additional passageway beingpositioned intermediate the passageways intersecting said sockets andthe periphery of two of said openings intersecting the per-iphery ofsaid additional passageway as well as that of a threaded passagewayintersectinga socket, so that the projections in said last mentionedopenings are squeezed between the screws in said additional passagewayand in the passageways intersecting the socket.

4. A junction block and support as claimed in claim 1 in which saidsupport comprises at least one projection 7 References Cited in the fileof this patent .UNITED STATES PATENTS- Keller May 3, 1955

